Method and system for controlling radio and television receivers at a distance



J. H. HOMRIGHOUS Feb. 20, 1945.

METHOD AND SYSTEM FOR CONTROLLING RADIO AND TELEVISION RECEIVERS AT ADISTANCE Filed Aug. 3, 1940 3 Sheets-Sheet 1 INVENTOR.

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MOD-AMP l-MLF'Ml/E HE C FULL Ml E Feb. 20, 1945. J. H. HOMRIGHOUS2,369,783

METHOD AND SYSTEM FOR CONTROLLING RADIO AND TELEVISION RECEIVERS AT ADISTANCE Flled Aug 3, 1940 5 Sheets-Sheet 3 lGN/TER L IGN/TE'R F 6 En KI Z M 7 w W 0 9 PER 8 EFDC 7 6 7 5 4 6 3 q 2 Patented Feb. 20, 1945UNITED STATES PATENT OFFICE METHOD AND SYSTEM FOR CONTROLLING RADIO ANDTELEVISION RECEIVERS AT A DISTANCE 27 Claims.

My invention relates generally to an improved method and system forcontrolling radio receivers at a distance.

One object of my invention is the provision of radio and televisionreceiving sets under the control of the operator at the transmittingstation whereby power supply may be connected to the receiving set.

Another object oi my invention is the provision of receiving stationsunder the control of the operator at the transmitting station wherebyany one or any number of the stations can be operated.

Another object of my invention is the selection for operation of any oneor several of a number oi controls and to change this selection ofcontrols to any other combination at the will oi a distant operator.

The present invention is an improvement on my prior inventions Serial#306,537 filed Nov. 28, 1939, now Patent Number 2,309,393, and Serial#334,864 filed May 13, 1940, now Patent Number 2,320,699. In thisapplication I have not shown a method for transmitting and reproducingsound but it is to be understood that either of the methods shown inabove noted applications may be used where desired between certain typesof stations.

Other objects, features, and advantages of my invention will appear fromthe following description taken in connection with the accompanyingdrawings illustrating an embodiment thereof in which:

Figures 1 and 2 are simplified diagrammatic views of a televisiontransmitting station and a television receiving station, respectively,illustrating the principle applied in this invention.

Figure 3 is a motor device for generating control frequencies.

Figure 4 is an end view of the disk shown in Figure 3.

Figures 5, 6, 'l, and 9 are control circuits for scanning and interlaceoperations.

Figure 8 is a simplified diagram showing circuit figure numbers used ingenerating the sweep frequencies,

Figure 10 is a tuned station control and circuit.

Figure 11 is a photo-electric tube circuit.

Figures 12 and 13 show picture or video control characters, reproducedat the receiver, and a photo tulle circuit.

Figure 14 shows selective devices responsive to certain definitefrequencies.

Figure 15 shows picture characters for use at the transmitter to producedennite frequencies."

Figures 16 and 17 show picture characters, or code reproduced at thereceiver.

Figure 18 shows circuits arranged tor code operation.

Figure 19 shows an arrangement for several separate codes.

In Figure l the numeral l designates a cathoderay pick-up tube of theconventional type, and is known as an Iconosoope. It is to be understoodthat other types 0! tubes may be used such as the Orthiconoscopedeveloped for perpendicular scanning of all points on the mosaic; or thetube, known as the image dissector may be used instead of the oneillustrated.

As shown the tube comprises a mosaic, photoelectric screen on which alight image of the object is projected and an electron gun forgenerating a ray of electrons directed at the screen, and two sets ofdeflecting plates for deflecting the electron ray at the line and fieldfrequencies, so that it is caused to scan the screen. It is to beunderstood that electromagnetic means may be employed for deflecting theelectron beam. The picture and certain other control characters arethereby developed and fed by an output connector 2 to a modulatingamplifier 3.

A carrier wave is provided by an oscillator l in the power amplifier i.The oscillator 4 may be arranged to supply several different frequenciesor diiferent oscillators may be switched in and out of the circuit inorder that several carrier waves may be used. The carrier is modulatedby the frequency band video or picture signals through the modulationamplifier 3. The signals from the amplifier 5 are supplied by aconnection 6 to the mixing circuit 1. Certain control characters forgoverning the scanning action at the receiving set may be transmitted asvideo signals, as also covered in my prior application, and when this isdone the signals from amplifier I are supplied by the connections 6 andi direct to the antenna 8.

The numeral 10 designates a generator for producing pulsating voltagewaves or waves of sine iorm ior controlling the sweep frequencies at thedesired frame frequencies. These sweep and line frequencies are suppliedto the deflecting plates of tube I. The sine form wave may through themedium of amplifier ll modulate another carrier produced by oscillator12 in its amplifier stage II. When it is desired by the operator totransmit a separate synchronizing frequency for controlling the scanningaction at the receiver. The

signals from the amplifier ii are fed to the mixer circuit 1 through theconductor It.

The two carrier waves, one modulated by a single control sweepfrequency: the other, modulated by video signals, are mixed in the mixercircuit I and fed to the common antenna 9 for transmission by radio.

The control signals are transmitted in the form of a sine wave which arechanged or rectified at the receiving station before they are used tosynchronize the scanning action with the transmitter.

The antenna l8, Figure 2, receives the carrier signals from thetransmitter antenna 9 to a tuned station control equipment circuit i6.These signals may come in over a single carrier whenever the controlvoltages are to be generated from the picture signals, or two carriersmay be employed when it is desired to have the control for the sweepnals transmitted as a definite frequency on a s -carrier.

The tuned station control, circuit it functions only when a carriermodulated by a particular frequency is received. to switch the incomingsignal from the tuned station control circuit to the radio frequencyamplifier l1 and to close the battery supply to the receiving set.

An oscillator ll reacts with these signals in the first stage IS on thesuperheterodyne principle to produce in one case a single intermediatefrequency signal which is supplied to the video intermediate stage IIIand at stations operating from two carriers, the oscillator 18 reactswith these two signals in the stage I! to produce two intermediatefrequencies which are fed to the two stages 20 and II.

After suitable amplification, the video signals are detected at 22 andfed by a connection 23 to a reproducing or picture tube 24. The device24 is represented as being in the form of a cathode ray tube of wellknown construction. and comprises a fluorescent screen, an electron gunfor developing a ray of electrons, directed toward the screen, and twosets of electrostatic plates for deflecting the electron ray at the lineand field frequencies to cause it to scan the screen. It is to beunderstood that electromagnetic means may be employed for deflecting theelectron beam. The video signals are applied to a control electrode ofthe electron gun to change the intensity of the electron ray inaccordance with picture or video signals.

Blanking signals may be obtained in accordance with the system shown inmy prior applications Serial #334,864.

The picture tube 2. reproduces a certain character at 25 which is pickedup by the photo-tube shown in the circuit of Figure 11 which in turnoperates over connection It to a holding device in the station controlcircuit ll whereby the apparatus will continue to be supplied withbattery until such time as the transmitter either goes on the air or theimage for producing the character at 25 is no longer transmitted.

In certain instances a more economical and different method ofinterpreting video signals is desirable and I have provided such adevice in Figure 14 to be explained more fully later and as shown in Fiure 2 it is fed from connection 21 eliminating the picture tube 24 andthe necessity for sweep signals. The connection 28 is for holding thestation control circuit III in operated condition.

Referring to the intermediate frequency stage II, which in certaininstances may receive the control signals and through the action of thesec- 'ond detector 28 the output of which is a voltage wave of sine formthat is fed to the sweep Benerator and amplifier circuit 88 where aftersuitable amplification it is changed or rectified and used to controlthe vertical scanning and this output voltage wave is also used toproduce a higher frequency for synchronizing horizontal line scanning inthe amplifier generator device 30 using circuits similar to those usedin .the transmitter, which will be explained in more detail later.

The picture control characters reproduced at SI and supplied to suitablephoto-tube circuits are for generating the synchronizing frequencies atthe receiving station, thereby eliminating the necessity of transmittingcontrol frequencies. This will also narrow the frequency band required.

Referring to Figure 3, the numeral 32 represents a motor which isoperated from the local power supply and has a variable speed fromapproximately 1500 R. P. M. to 1800 R. P. M. or one revolution perframe. The drum 3! has two black bands 34 and 35, each of which extendsover one half of the periphery and are located adjacent the oppositeedges of the drum 33 which drum is directly connected to the motor shaftso that by rotating it in front of the transmitting tube 1, two

short black lines will appear alternately. but separated on the mosaicwhich will be reproduced at the picture tube in the receiving set asshown in Figure 13 and are used for controlling the sweep frequencieswhich will be further explained later.

Thus it will be seen that each mark or sign on the mosaic is definitelyidentified with a field and that it is also definitely related to thespeed of the motor which is two fields per revolution.

Connected to the motor shaft, is a disk of light polarizing material 36,revolving past stationary pieces of light polarizin material 31 and 38and also separate sources of light 39 and ill respectively.

The revolving and stationary members are better shown in Figure 4. Thedisk 38 is of polarizing material, having a certain part painted orblocked out so that by rotating it in a clockwise direction past itsstationary members of polarizing material I! and l! and between itssources of light 39 and II and their respective photo-cell II and I! theintensity of the ht reaching each photo-cell will uniformly vary romzero value to maximum value and back to zero during one half of arevolution and during the other half of the revolution there will be nolight change. The photo-cell ll and 42 are placed one hundred and eightydegrees apart and changes in intensity of light will alternately effecteach photo-cell.

A system for producing the proper sweep frequencies is shown in Figures5 to 9 inclusive.

Referring to Figure 5 I have shown a circuit for producing analternating current from the variations of light occurring in thephoto-cells ll and 42 which are the photo-cells shown in Figure 3. Thesephoto-cells control the grid excitation of grids 43 and 44 of amplifiertubes 45 and B. The anodes 41 are connected in parallel through theprimary transformer winding 48 to the positive side of voltage divider49. The cathodes 50 are connected in parallel to an intermediate pointof the voltage divider 19. The cathode II of photocell ll is connectedto the grid 43 of tube l5 and through resistance 52 to negativepotential at the voltage divider, thereby maintaining the grid II at anegative potential with respect to cathode Ill and plate 41. The circuitis so arranged therefore, that an increase in the intensity of light onassures the photocell I will increase the output current of tube ll. Thephoto-cell 4! has its anode SI connected to the grid 44 of tube ll, andit is maintained at a positive potential with respect to its cathode It.This causes a decrease in the current of tube 46, upon increasing theintensity of light directed toward the photo-cell 42 other ampllfiertubes may be connected in parallel to increase the output.

Therefore since the plate circuits of tubes II and 46 are in parallelthe rotation of the disk 8| will alternately operate the photo-cells lland 42 to produce a continuous rising and falling current in the primarywinding I of a transformer whereby, alternating voltages are induced inthe secondary winding.

when it is desired to control the receivers by a definite frequency fromthe transmitter these voltage waves generated by Figure 5 are modulatedon a sub-carrier as explained in connection with Figure l. and aretransmitted by radio to the receiving set to control the field and linefrequencies for controlling the deflection of the electron ray in thereceiving tubes. These voltage waves are also used to control the lineand field saw tooth wave at the transmitting tube.

In this invention I employ frequency multiplying circuits for thepurpose of producing the high frequency required for horizontal linescanning. The field frequency is obtained as described above and fromthese frequencies the higher line frequencies are produced.

Referring to Figure 6, two stages of frequency multiplication are shown.The secondary 66 is inductively connected to the primary winding It inFigure 5 to supply alternating pulses to the tapped secondary and inturn to the full wave rectifier tube 51 which delivers twice the numberof pulses or cycles to the tuned filter comprising the condenser 58 andthe next transformer pri-- mary winding 59. This double cycle signal issupplied by the tapped secondary 60 to the full wave rectifier tube 6i,where it is again doubled and fed to the succeeding transformer primaryCI. The tapped secondary it delivers alternating current to the nextstage and so on until the desired high frequency for line scanning isobtained.

In this invention I prefer to use doublers and obtain an even number oflines per field or frame and for interlace scanning each field wouldhave an even and equal number of lines.

From the above it will be seen that by changing the speed of the motorin Figure 3 the number of fields or frames per second would be changedbut the number of lines per field would remain the same. This willeliminate interference with local power, and it is one method that canbe used that will make it difllcult for other than predeterminedreceiving sets to obtain the information transmitted.

To produce the desired output wave of saw tooth form for field and linescanning, I employ a grid controlled discharge tube circuit shown inFigure 7, where voltages induced into the transformer secondary winding65 drive the grid of tube 88 positive, discharging the condenser 81through the tube 66. Thus by alternately charging the condenser 81through the resistance It and discharging it through the tube It a sawtooth voltage is generated.

In Figure 8, I have shown. diagrammatically, the circuit figure numbersused to produce the required frame and line frequencies: severalcircuits ofl 'igureiimaybeusedbutitistobeun- 3 derstood that thiscircuit may represent only one stage With further reference to Figure 8.I have provided two switches 89 and II for shorting out one or morestages of doublers so that the horizontal lines may be varied at thewill of the operator. One of the switches or keys may also change the avoltage on the focusing electrode in the CR tubes ture However,

to thereby change the size of the spot of electron on the screen.

The diagrammatical arrangement of circuit figure numbers shown in Figure8 will be the same arrangement of circuits employed at the receiver whencontrol frequencies are developed from characters reproduced on thescreen of the picwhen a sine form voltage wave is transmitted to governthe scanning action at the receiver the schematic arrangement will thesame, except gure 5 should be omitted.

In the present invention in order to produce interlace scanning from asine form voltage wave it is necessary to identify every other field andin some manner cause the horizontal lines of one field to fallin betweenthe lines produced in the second field or the lines of one field areeven num- Ibgred and in the second field they are odd numred.

In order to accomplish the interlace features noted above, I employ thecircuit shown in Figure 9. In this circuit voltage waves of sine formare supplied from the circuit of Figure 5 or are transmitted to thereceiving set as previously explained in connection with Figure 2, overthe conductor Ii to a full wave rectifier 12 of conventional design. Theoutput wave form is shown at it. These pulses are fed through theprimary winding 14 of a transformer to the wave forming circuit Figure7, to drive the grid of tube 86 positive discharging condenser 81thereby, producing saw tooth waves for vertical scanning.

These circuits are so arranged that the timing or synchronizing pulsesare also the trigger pulses for the discharge tube whereby, the retraceis initiated.

In multiple. with the full wave rectifier I2, is a half wave rectifierII, having an output wave form as shown at it. The pulses from therectifier it are supplied by connection IT to an amplifier It, theoutput of which is connected through II to battery. pulses will inducein the secondary a voltage potential in conductor from that furnished bythe battery 86 for the duration of each pulse. The lead Ill suppliespotential to one of the vertical deflecting plates of the cathode raytube 2., Figure 2 through a variable resistance (not shown) forcentering or adiusting the vertical movement of the electron spot.Another lead from the battery 86 would supply potential to the oppositevertical deflecting plate through another resistance. The potential onthe plate of amplifier 18 is adjustable at 8i, depending upon the. spacebetween even or odd lines.

fleld pulses, eliminating any necessity oi! transmitting by radiosynchronizing pulses, other than one sine form wave oi field frequency.

From the above description it will be seen that the line pulses aredefinitely locked with the field pulses, or in other words, the samepulse that triggers the vertical deflection also, through multiplyingcircuits, supplies the trigger pulses for line scanning.

Furthermore, from the above description, the control of the field andline deflecting circuits at the receiver from the sine form voltage wavetransmitted by radio from the transmitting station will cause thecathode-ray or electron ray in the viewing tube to be in exactsynchronization with the cathode-ray in the pick-up tube whenever thereceiving station is tuned to the proper carrier wave.

At any time or instant that the receiver is tuned to the same carrierwave of the transmitting station, the deflecting circuits willautomatically be in step. Suppose that at a certain instant thecathode-ray or electron ray in the pick-up tube is focused on mid-pointof line number I15. Now, since a single frequency or control voltagewave generated at the transmitter station times the deflection of boththe field and the horizontal lines at both the transmitting station andreceiving station, the cathode-ray at the iewing tube wouldautomatically be focused at the mid-point of line I15 on the screen ofthe viewing tube, and furthermore, since I have provided through themedium 01' a half wave rectifier, Figure 9, mean for associating thepositive pulse in each cycle of the control voltage wave with a certainheld, the focused electron ray in each tube would also fall in theproper vertical location in each field. The picture or symbols producedfrom this system will be approximately as high as they are wide sincethere is very little need of reserving space at the bottom of thepicture for synchronizing pulses.

With further reference to Figure 9, the switch or key 82 is thrown toof! position whenever it is desired to send pi tures or symbolsbyprogressive scanning, in' which case there would be no need for changingthe position of the horizontal lines in the fields. The changing fromprogressive to interlace scanning is another method that would bedilllcult for uninstructed receiving station operators to figure ou Insome cases it may be desirable to operate the movement or the electronbeam at a slow rate and for that purpose I have provided at the receiveran optional feature, or the positive pulses from the connection 11Figure 9 are fed through connection 83 to a relay 84 instead of goingthrough the tube 18. This relay ll operates its spring 85 upon receivinga positive pulse to change the potential oi battery 86 which battery issupplied to one of the vertical deflecting plates through a variablecentering resistance and as previously explained in connection with thetube 18 this potential change causes the lines of one held to fall inbetween the lines of a second field."

With reference to the relay 84 it may be used for an entirely differentpurpose and as shown by the reference numeral 81 it operates the springs88 and 88 to switch the input circuit 80 from one output circuit at to asecond output circuit 92 which will be explained in more detail later.

From the preceding explanation it will be seen that many combinationsmay be derived, for instance, at certain predetermined time intervalsduring the day messages or pictures may be transmitted by progressivescanning: other time intervals interlace scanning may be used. The fieldirequency may be changed from slow to fast and vice versa at the optionof the operator at the transmitting station; also the number oi linesper field may be changed at predetermined intervals.

Referring to Figure 10, I have shown a station control stand-by circuitor, in other words, a circuit that will only operate when the propercarrier wave is received and normally this circuit is without batterydrain. The modulated carrier is received from the antenna ll overconductor ill, spring 94, conductor 05' to the receiving tuned stationcircuit consisting oi the following equipment an antenna coil 96 andcondenser 81 which may be adjusted for various carriers and a crystaldetector which may be a tube detector provided with a power supply.After detection the signals are supplied to a relay or auxiliary device99 which operates in the low or audio frequency range and may be similarto the one shown in my prior application Patent Number 1,460,814. Thenumber Hill represents a lav-pass condenser.

The carrier at the transmitter is first modulated by a particularfrequency for a short interval of time. The method of modulation to bemore fully explained later. The duration of this preliminary frequencywill actuate the spring iii and close the circuit to the slow actingrelay or circuit closing device I02. The relay N2, in operating itssprings Hi3, closes the battery supply circuit to all the tube filamentsin this receiving set, and also to the heating element In forcontrolling the bimetal spring or circuit changing device 94. The relayIII! will remain energized through the action of spring IN during theinterval of the low frequency modulation or until such time as theblmetal spring becomes sufllciently heated from its element IM. todeflect and open the circuit to the antenna coil 98, at follow up springI05 and to place ground on the antenna coil I06 through the closing ofspring as and Ill.

The operation or the bimetal spring 94 to switch antenna coils from coil96 to coil "II is slow in order to allow some time for the filaments ofthe several receiving tubes (one tube shown at Hill) to becomesufllciently heated for proper operation. At the time of the switch overthe preliminary frequency received over the antenna should be ended andvideo signals for code operation and other controls should be receivedfrom the antenna on the same or a different carrier and developed in thereceiving set equipment.

The operation of relay I02 also closes the B battery supply to the anodecircuits for the several receiver tubes at springs lilil. The relay N2must remain in an operated position during the transmission of videosignals. One method used to accomplish this feature is to provide aphotocell iiil Figure 12 to pick up a beam of light at a particular spotor location on the screen of the viewing tube and as shown at III. Thisspot or point i ll is under the control of the operator at thetransmitter and may be produced from one of the marks on the drum 33Figure 3 or it may be produced in a manner to be described in connectionwith Figure 15. Referring to Figure 11 I have shown a photo-cell litwhich may be the photo-cell Ill in Figure 12. This cell is respongive tovariations of light intensities and will also permit current to flowwhen exposed to a steady beam of light of sufficient intensity. lightdirected toward the photo-cell will change the grid potential ofamplifier tube H3. The anode of tube H3 is connected through the lowerwinding of relay I to the positive terminal of the voltage divider I ll.Therefore a steady light on the spot iii directed toward the photo-cellIII will cause current to flow in the lower winding of relay I02,thereby maintaining the relay operated as long as the spot Iii remainsilluminated to release the receiving set all that is required is totransmit signals to make the spot Ill dark which will release the relayI02 and also render the receiving station inoperative until it is againsignaled as previously described. I

The anode of tube H3 may be connected through the winding of anotherrelay Ill instead of a winding of relay I02. The spot Ill may be placedat different locations on the tubes of different receiving sets so thatany one of a number of receiving sets operating on the same carrier maybe released independently of the other receiving sets. By keeping thespot Ill dark for a short or indefinite interval the relay ill willrelease opening the battery supply to the various tubes.

With reference to Figure 13 I have shown two fields, A and B, reproducedat the viewing tube showing control character or marks 6 and II I. Thesemarks or characters are produced by rotating the drum 33 Figure 3 infront of the transmitting tube. The marks Iii and ill will alternatefrom light to dark and back to dark again, or the mark lit field A willbe light and in field B it will be dark while mark H1 is the reversefrom this or at the time of field A mark Ill will be dark while mark IIt will be light.

Light from these characters H6 and ill is directed through suitablelenses to photo-cells Ill and H9 respectively which may be thephoto-cells ti and 42 shown in the circuit of Figure 5. Thesephoto-cells will operate in the circuit of Figure to alternatelyincrease and decrease the current in the primary winding Iii aspreviously described whereby, the field and horizontal line scanningfrequencies are produced at the receiving stations using the figurenumbers as shown in Figure 8.

In my prior application Patent No. 2,309,393 the characters forproducing synchronizing frequencies were developed at the rate ofpicture or frame frequency instead of as shown and described in thisapplication of having the characters developed at the rate of fieldfrequency.

With further reference to Figure 13, some means must be provided forautomatically starting the scanning operation, when the sweepfrequencies are controlled from characters reproduced at the unattendedreceiving station. When the battery at the receiver is first switched onthe electron beam in the cathode-ray tube will be directed toward theupper left corner of the viewing tube as indicated by the spot I20. Thefields A and B in Figure 13 are shown rotated one hundred eighty degreesor like they would appear on the mosaic at the transmitting tube,therefore the scanning would start from the lower right hand corner andprogress toward the left and top in Figure 13. The electron ray willrest at this point [20, which may be an adjustable location outside ofthe normal picture area, since the horizontal and vertical deflectingcondensers (like 8'! Figure 7) have been charged to maximum capacitywhich would cause the electron ray to be deflected further than normal.The discharge of these condensers is ac- 5 complishedby modulating testpulses on the carrier by placing test fields or patterns izrfront of thetransmitting tube. The light caused by the impact of the electrons atthe spot Ill d is in multiplewith the photo-tube I Figure 5, throughconductors III and ill.

The sender or test pattern placed in front of the transmitting tube issimilar to the reproduced picture or held in Figure 13 except that thetop of pattern would be dark gray in color, ally fading to white in thecenter and from the center toward the lower edge it would gradu getdarker and at the bottom of pattern it would be black, which is the sameas upper half of Figure 15. From the above it will be seen that the spotIII would gradually vary in ight intensity which would give the firsttrigger pulse to the sweep control circuits of Figure 5. The function ofby-pass condenser I and the resistance III is to prevent the operationof the sweep control circuits from high frequency pulses caused byscanning and also by up or,retrace between horizontal lines.

The test pattern after an interval of a few fields would be taken awayfrom transmitting tube but the reproduction of the marks or characterson the drum of Figure 3 would still continue during the sending andreceiving of any other information.

with reference to Figure 14, I have shown another method 01' receivinradio signals originating from a cathode-ray camera tube, and as thepicture shown in Figure 15 is placed in front the camera tube itselectron ray wlllscan an image of the designs or patterns for producingtwo pulses of current. One pattern occupying the upper half of thepicture and the second pattern on the lower half of the picture. Each ofthese patterns is similar to the test pattern described in connectionwith Figure 13 and it is to be understood that a picture may contain oneor any desired number of patterns.

The test patterns shown in Figure 15 will produce a frequency of 120cycles per second with fields per second.

From the above description it will be seen that many frequencies may bemodulated on the carrier. At the receiving station the cathoderay tubeand associated sweep generator circuits will not be required as shown inFigure 2. The output from the second detector Figure 2 is fed through apower amplifier l2! Figure 14 to a circuit having a tuned or harmonicrelay I21 which is well known in the art and as shown it has a weightedor tuned armature I28 which only responds to a certain frequency. Thecondenser I28 will by-pass extremely high frequencies caused by the gapbetween lines or retrace interval. The vibration of the relay armatureI28 from a suitable frequency caused by a particular pattern attransmitting tube will close the circuit to slow release relay m. Thisrelay in energizing will place ground on conductor Ill extending back torelay ill! in the station control circuit Figure 10 to hold the stationin operative condition as previously explained.

The relay II! will continue to vibrate its armature as long as theparticular frequency is received. However, when placing a picture havingmore than two patterns in front of the transmitting tube a higherfrequency is obtained which will operate the alternating current relayIII in series with the resistance it! and condenser I 34 which are inresonance for this particular frequency and will not-operate on thelower frequency. The relay I82 closes through its spring contacts andthe contacts of slow release relay I" the circuit to the igniter I"which may be placed in a bomb.

From the above description it will be seen that I have provided a novelsystem for generating various frequencies at the will of the operator atthe transmitting station {or controlling devices at a remote distance.Furthermore, as previously stated, the generation or sweep frequencieswere not required to operate the apparatus 01' Figure 14. However, Ihave provided another method of selecting different circuits bytransmitting the field sweep frequency to the receiving station and byemploying the circuits of Figure 9 as previously described relay illwill operate to alternate from one circuit Figure 14 through conductorIi to another circuit of Figure 14 through conductors 92.

With reference to Figure 16 I have shown a system for, producing variouscombination or numbers or locations reproduced on the screen of aviewing tube, horizontal rows are numbered from bottom up, and verticalcolumns are numbered left to right, and as shown, the black space, I38,reading up and across would be forty three and so on.

In Figure 16 I have shown two sets of figures of twenty five numberseach. This will further complicate the system. However in Figure l! Ihave shown one set of figures but having 100 squares the square iIIindicated black reading up and across would be ninety six, etc. Severalor these squares may be used at one time and for various purposes.

These symbols may be used for transmitting various form or information.For instance certain sets of numbers may explode bombs, others maycontrol a robot vehicle. and still others may be used for telegraph orBoudat code symbols. The alphabet may be used similar to that shownwhere C is number thirty-seven, E is number 67, etc. giving almost anunlimited number of combinaticns.

Figure 19 shows several separate areas for transmitting simultaneouslyseveral codes for different purposes, somewhat similar to Figure 18. Forinstance the large square ill may be for the purpose of controlling someselective devices in the receiving station, also the location or thespot or mark iii in Figure 12 for holding or releasing the receiver maybe in this location. The other area may be used for other purposes asdesired.

Figures l5, 16, 1'1. and 21 show the patterns or frames as they arereproduced at the viewing tube. It is to be understood that these willbe reversed at the transmitting tube on account of the lens system.

The numeral I39 Figure 16 shows a side view of the frame work forproducing the desired images upon mosaic of the camera tube. Thisstructure consists 01' very thin material placed together forming hollowsquares, one hollow square for each two number location: such as thelocation forty-three is a hollow square represented by the numeral I38,etc. The numeral llil represents a square peg having a black face. Thesepage are placed in the hollow squares when it is desired to transmitsome certain square area as black and all others as white.

At the unattended stations using this code system for controlling robotsor explosives, 1 provide a photo-cell such as Ill and I42 Figure l! foreach location naught eight and naught nine that is to be used forgoverning the time of the explosion of a bomb or a mine. Either of thesephoto-cells may be substituted for the photo-cell ii! in the circuit orFigure 11. With reference to Figure 18 I have shown two relays ill and Ieither of which may be substituted for the relay 4 il in a circuitsimilar to Figure 11. Light directed from location naught eight andnaught nine into photo tubes Hi and ii! respectively will operate thesprings of relays ill and I to close the circuit to the igniter ill.

I do not intend that the present invention shall be restricted to thearrangement 0! parts or to the particular form as herein set forth, butcontemplate all modiiication and changes therein within the terms of theappended claims.

Having thus described my invention, I claim:

1. In a radio system, a main receiver including electron tubes. an energzi circuit for the said electron tubes, a control receiver including asignal detector, a signal device, an output circuit for said detector,including said signal device operable from modulated signals, a powersupply circuit, a slow acting switching mechanism having a currentsupply circuit energized by the operation of said signal device forelectrically connecting said power supply circuit to the said tubes, andmeans for impressing upon said control receiver and main receivermodulated carrier waves.

2. Th system, in accordance with claim 1, in which there is provided athermal switch having a winding included in the energizing circuit forthe said tubes, whereby the switch may be flexed when the said tubes areenergized to there y render the said control receiver inoperative whenthe main receiver is receptive to modulated carrier waves.

3. In a radio system, an antenna, a main receiver including a firstantenna coil connected to said antenna, an energizing circuit for saidmain receiver, a stand-by receiver including a second antenna coilconnected to said antenna in an operative condition for the reception ofmodulated carrier signals, control means operated by said stand-byreceiver upon the reception of said modulated signals, for energizingsaid main receiver, said energizing circuit including switching meansfor lay-passing radio frequency energy around said second antenna coilinto said first antenna coil to render said main receiver operative tothe reception of modulated carrier signals.

4. In a television system, a cathode my viewing tube provided with ascreen, a main receiver network for producing images from receivedpicture signals on said screen, an energizing circuit for said mainreceiver, a stand-by receiver, control means operated by said stand-byreceiver for energizing said main receiver upon the reception ofmodulated carrier waves, and means for impressing upon said mainreceiver predetermined carrier waves of another frequency modulated bysaid picture signals.

5. The system, in accordance with claim 4. in which there is provided aphoto electric device. sensitive to light from a certain location insaid images, and means regulated by said device for holding said controlmeans energized to maintain said main receiver in an operativecondition.

6. The system, in accordance with claim 4, in which said energizingcircuit includes switching means for rendering said stand-by receiverinoperative when the main receiver is receptive to modulated carrierwaves. m

1. A plurality oftelevision systems, in accordance with claim 4. inwhich there are provided photo electric devices sensitive to light fromdiiferent locations in the images on different screens for holding orreleasing their associated control means, whereby any one or any numberof said main receivers may be maintained in operation while the othersare rendered inoperative.

8. A plurality of television systems, in accordance with claim 4. inwhich there are provided photo electric devices sensitive to light fromdili'erent locations in the images on different screens for holding orreleasing their associated control means the said locations forreflecting light from said images to said photo electric devices are indifferent sections of said screen for diflerent groups or main receiversand in diiferent locations in said sections for difl'erent mainreceivers in said groups, whereby any one or any number of mainreceivers in any group or any number of groups may be maintained inoperation exclusively. l

9. A plurality of television systems, in accordance with claim 4, inwhich there are provided photo electric devices sensitive to light fromdifferent locations in the images on different screens for holding orreleasing their associated control means, the said locations forreflecting light from images to said photo electric devices are indifferent sections of said screen for diiferent grou s of main receiversand in diiferent locations in said sections for different main receiversin said groups, whereby means are provided t progressively select groupsof main receivers and to make a iinal selection to pick out one of saidmain receivers.

10. A plurality of television systems, in accordance with claim 4, inwhich there are provided groups of main receivers responsive todifferent carrier frequencies and groups of stand-by receiversresponsive to diflerent carrier frequencies. and in which there are alsoprovided photo elec- "tric devices sensit ve to li ht from diiferentlocations in the images on diilerent screens for holding or releasingtheir associated control means, the said locations for reflecting lightfrom ima es to said photo electric devices are in diilerent se tions ofsaid screen for different groups of main receivers and in differentlocations in said sections for diil'erent main receivers in said group,whereby means are provided to progressively select groups or mainreceivers and to make a final selection to pick out one of said mainreceivers.

11. The system, in accordance with claim 4. wherein there is provided atransmitter and means for producing different light values in successiveimages at said transmitter.

12. In a radio system, a main receiver, an energizing circuit for saidmain receiver, a standby receiver having a tuned circuit maintained inan operative condition for the reception oi sound frequency signalsmodulated on a carrier. a source of current supply. a circuit clos ngrelay, and relay means in said stand-by receiver responsive to receivedsound frequency signals for actuating the said circuit closing relay toelectrically connect the said source of current supply to the saidenergizing circuit.

13. In a radio system. a main receiver. an energizing circuit for saidmain receiver. a standby receiver provided with a tuned circuit in anoperative condition for the reception of signals modulated on a carrier.a source of current supply, control means in said stand-by receiverresponsive to received signals for electrically connecting the saidsource or current supp y to the said energizingcircuit, and a circuitchanging device actuated upon the energization of said main receiver torender the tuned circuits in the said stand-by receiver inoperative tothe reception of signals modulated on a carrier.

14. In a radio system, a main receiver provided with circuits tuned to apredetermined carrier frequency, an auxiliary receiver provided withcircuits tuned to the said predetermined carrier frequency and normallymaintained in an operative condition for the reception of signalsmodulated on a carrier. a circuit changing device, and control means inthe said auxiliary receiver responsive to signals received on a carrierof said predetermined frequency for actuating said circuit changingdevice to change the reception of the signals from the circuits in thesaid auxiliary receiver to the circuits in the said main receiver.

15. In a radio system, a main receiver provided with tubes. andassociated circuits tuned to a predetermined carrier frequency, anenergizing circuit for said tubes, an auxiliary receiver provided with adetector, and associated circuits tuned to the same predeterminedcarrier frequency. saidauxiliary receiver normally maintained in anoperative condition for the reception of signals modulated on a carrier,a source or current supply, a circuit closing device, a relay in saidauxiliary receiver responsive to received signals for controlling thesaid circuit closing device to electrically connect the said source ofcurrent supply to said en rgizing circuit, and circuit changingmechanism actuated upon the energization of said main receiver forchanging the reception of signals from the circuits in the saidauxiliary receiver to the circuit in the said main receiver.

16. In a radio system, a main receiver provided with circuits tuned to acarrier frequency, an auxiliary receiver provided with circuits tuned toa difierent carrier frequency and normally maintained in an operativecondition for the reception of signals modulated on a carrier, a circuitchanging device, and control means in the said auxiliary receiver resonsive to received signals for actuating said circuit changing devicesto change the reception of signals from the tuned circuits in the saidmain receiver, whereby the reception of signals is changed from acarrier of one frequency to a carrier of another frequency.

17. In a television system. a cathode ray viewing tube provided with ascreen, a main receiver provided with suitable circuits for producingimages on the said screen from received picture signals, an energizingcircuit for said main receiver. an auxiliary device operated by receivedsignals, a current supply circuit. control means operated by said devicefor electrically connecting the said current supply circuit to the saidenergizing circuit, and means for impressing upon said main receiver apredetermined carrier modulated by said picture signals.

18. In a television system, a cathode ray view- Ing tube provided with-ascreen, a main receiver provided with suitable circuits tuned to apredetermined carrier frequency for producing images on said screen fromreceived picture signals, an auxiliary receiver provided with suitablecircuits tuned to a predetermined carrier frequency for the reception ofsignals modulated on a carrier, and control means in the said auxiliaryreceiver responsive to received signals for switching the reception ofsignals from the said auxiliary receiver to the said main receiver.

19. In a television system, a cathode ray viewing tube provided with ascreen, a main receiver provided with suitable circuit tuned to apredetermined carrier trequency for producing images on said screen fromreceived picture signals, an auxiliary receiver provided with suitablecircuits tuned to a diil'erent carrier frequency for th reception ofsignals modulated on a carrier, and control means in the said auxiliaryreceiver responsive to received signals for switching the reception ofsignals from a carrier oi one irequency to a carrier or anotherfrequency.

20. The system in accordance with claim 19 in which there is provided adevice sensitive to light from a particular location in said images, andmeans regulated by said device for holding the said control meansoperated to maintain said main receiver in an operative condition.

21. In a television system, a plurality oi cathode ray viewing tubeseach provided with an image screen, a main receiver for each of the saidtubes, each of the said receivers provided with suitable networks forproducing images on its associated screen from received picture signals,means for impressing upon said main receivers a predetermined carriermodulated by picture signals, and means under the control of the imagesappearing on the said screens for rendaring any one or any number saidreceivers inoperative to the reception of picture signals.

22. In a television system, a plurality of cathode ray viewing tubeseach provided with an image screen, a main receiver for each of the saidtubes, each of the said receivers provided with apparatus and suitablecircuits for producing images on its associated screen from receivedpicture signals, means for impressing upon said main receivers apredetermined carrier modulated by picture signals, and means in eachrecelver sensitive to different intensity or light on its associatedscreen for holding the receiver in an operative condition for thereception 0! picture signals.

23. In a television system, a plurality of cathode ray viewing tubeseach provided with an image screen, a main receiver for each of the saidtubes, each of the said receivers provided with apparatus and suitablecircuits for producing images on its associated screen from receivedicture signals, means for impressing upon said main receivers apredetermined carrier modulated 'by picture signals, and means under thecontrol of the images appearing on the said screens for discontinuingthe images on any one or any number of said scream.

device in each or the said receivers sensitive to different intensitiesof light Irom the said holding and release point on its associatedscreen, whereby any one or any number of the said main receivers may bemaintained in operation while the others are rendered inoperative.

25. In a selective communication syst m, a plurality of cathode rayviewing tubes each provided with an image screen, a receiver for each ofthe said tubes, each of the said receivers providedwith apparatus andsuitable circuits for producing images on its associated screen fromreceived picture signals, means for impressing upon said receiver apredetermined carrier modulated by picture signals a holding and releasepoint in dlflerent locations on each one of the said screens forreflecting different intensities of light, a device in each or the saidreceivers sensitive to diil'erent degrees of light from the said holdingand release point on its associated screen, whereby certain of the saidreceivers may be maintained in operation for a period oi time while theothers are rendered inoperative and thereafter any one or any number ofthe operating receivers may be rendered inoperative.

26. In a selective communication system, a sending station, a pluralityof receiving stations, means for transmitting energy therebetween tooperate the said receivers including a source or electrical signals, andmeans under the control of the said sending station for altering thelectrical signals to maintain any one or any number of the saidreceiving stations in operation while the remaining receiving stationsare rendered inoperative.

27. In a radio communication system, a transmitting station, a pluralityof receiving stations, means for transmitting signals modulated on acarrier therebetween to operate said receiving stations, and means underthe control or the transmitting station for changing the said signals toselect any one of the said receiving stations exclusive of all otherstations to receive the said modulated signals.

J OHN H. HOMRIGHOUS.

CERTIFICATE OF CORRECTION.

Patent No. 2,569,783. February 20, 1915.

JOHN H. HOHRIGHOUS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 7,sec- 0nd column, line 52, claim 16, after the word "said" insert-auxiliary receiver to the tuned circuits in the said--; and thattheseid Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 19111 day of June, A. n. 1915.

Leslie Frazer (Seal) Acting Commissioner of Patents.

